Câu 1. Ta có:
a) \(\left[ {400 - \left( {40:{2^3} + {{3.5}^3}} \right)} \right] :5 \)
\(\;\;\;= {{400} \over 5} - \left( {{{40} \over {8.5}} + {{{{3.5}^3}} \over 5}} \right) = 4\) ;
b) \({{{{22}^2} - {{11}^2}} \over {11}} = {{{{\left( {2.11} \right)}^2}} \over {11}} - {{{{11}^2}} \over {11}} \)
\(\;\;\;= 4.11 - 11 = 33\)
Câu 2. Ta có
\(n = \overline {ab} + \overline {ba} = 10a + b + 10b + a \)\(\;= 11a + 11b = 11\left( {a + b} \right)\).
